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Shedd spurs mating of tiny frogs that are shrinking in numbers

A Mantella frog on a finger shows significant size. | Brenna Hernandez~John G. Shedd Aquarium

It might be cold outside, but it’s steamy behind the scenes at the Shedd Aquarium’s frog exhibit.

Behind the public displays and away from view, 48 critically endangered frogs representing four species of mottled Mantella frogs are in the middle of their mating season.

It’s good that it’s happening here, because in the wilds of Madagascar and its nearby islands, the colorful frogs with poisonous skin are endangered due to habitat loss, said Stacy Wozniak, a senior aquarist who oversees the Mantellas at the Shedd.

Although the population is still substantial, “it’s constantly getting smaller and smaller,” Wozniak said.

The Shedd has focused on breeding the frogs for the last two to three months, with impressive results, said George Parsons, director of aquarium collections.

The male frogs – which like their mates are about an inch tall and vary in color from gold to green – began “calling” the females in January, Wozniak said. The calls sound like a bird chirping and are meant to notify female frogs of a desire to breed.

Each female Mantella frog can produce as many as six “clutches,” or batches of eggs in a mating season, with 60 eggs per clutch, he said.

The females “get so large that you can see the eggs through their skin,” Wozniak said.

Very few tadpoles have been lost this season, which Wozniak credits to the Shedd’s ability to supply the frogs and tadpoles with the proper nutrients. The Mantella frogs eat crickets, fruit flies and springtails, a type of insect.

The new frogs will be introduced to the public exhibit – which has 25 frogs – in about two to three months.

There, visitors can look – but don’t touch. The Mantellas secrete pumiliotoxins through glands in their skin that can be poisonous.